Drawing on experience

Jun 22, 2017
Boating history ,Cruising ,General Interest

There’s more to the humble hydrographic chart than meets the eye, asserts Lindsay Wright.

A marine chart is no mere piece of paper. On one level it may be a map of a designated stretch of coastline – or ocean – showing depth contours and sea floor features. Properly used, it can save your life – or prevent drastic damage to your boat or crew.

But on a more fanciful level, a chart also does great service spread over a kitchen table to plan next summer’s cruising itinerary while winter gales thrash around outdoors.

A chart – calling it a map will earn withering scorn from navigation tutors and experienced seafarers – is the culmination of painstaking survey work and a long tradition of navigational excellence. One of the hardest chartwork lessons can be learning to place your entire faith in a piece of paper – but they’re rarely wrong.

If someone tells you they hit an uncharted rock – it normally means that they didn’t know where they were on the chart. Having said that, I once had a close call with an isolated rock off North Cape, which was on a fold in the chart. The chart had been folded so many times that the rock had been obliterated – it was time to buy a new one.

In this age of relatively cheap and accurate GPS chart plotters the paper chart is at risk of becoming redundant – but there’s great satisfaction to be had in plotting your own position on a chart and keeping the skills alive.

You also get to use those nice navigation tools; well-worn bronze dividers and parallel ruler, a hand-bearing compass or course plotter, a 2B pencil (easier to erase) and rubber. Precise chartwork is draughtmanship of a high order.

“You can’t trust electronics at sea – electricity and salt water don’t mix,” the old hands used to grizzle. But modern boats are generally dry inside and don’t drizzle through the deck like their wood-planked forebears often did in a seaway, and modern electronics don’t fizzle up and go fatal at the first whiff of salt water like earlier models did.

It’s pretty common these days to have four or five GPS receivers aboard – phones or hand-held units and iPads included – but it also pays to have a chart aboard to plot the fixes they relay. There’s a story around about an American yacht en route to New Zealand who paid for a RNZAF Orion to divert and tell the skipper his position over the VHF radio. His GPS plotter had died, and he hadn’t plotted a fix in the preceding four days. That gives a whole new meaning to ‘lost at sea.’

But charts can be compromised by liquid too. A friend once spent two days hove-to outside Port Vila waiting for another boat to arrive so he could follow it in because a cup of coffee had been spilled over his chart, deleting the finer details of the coral-bound approach channel.

Modern charts are the paper culmination of a surveying heritage that, in New Zealand, stretches back to 1642 when Abel Tasman produced the first verified charts detailing stretches of our coastline.

In 1769 Captain James Cook circumnavigated the country in HMS Endeavour conducting a running survey as he went and the resulting charts were produced as a three-volume set in Britain a few years later. The charts were said to be the best examples ever made at the time and his 1773 depiction of
Pickersgill Harbour (Fiordland) was in public use until 1997.

Sailing in his wake came mariners from the UK, France and Spain; sealers, whalers, timber and flax traders, Royal Navy ships taking kauri spars and, of course, missionary and immigrant vessels. All of these often drew localised charts and donated them for public use.

Spurred on by a few tragic shipwrecks, the Royal Navy got serious about charting New Zealand’s convoluted coastline and between 1848 and 1855 HMS Acheron and HMS Pandora conducted a detailed survey of the coast.

The responsibility for producing charts was passed to the fledgling Hydrographic Service of the Royal New Zealand Navy in 1949. It was estimated that about 80 percent of the charts then in use were based on survey data that was 100 years or more old.

In 1996, the NZ Hydrographic Authority, a division of Land Information New Zealand (LINZ) took over and the first private sector surveys began. LINZ now has about 196 charts in the New Zealand catalogue – including South West Pacific islands, the Southern Ocean and Ross Sea Dependency which are updated weekly by the NZ Notices to Mariners.

The NOAA (National Oceanic and Atmospheric Administration), the US body that’s produced the thousands of charts required to cover continental US waters and their offshore territories, announced in April 2014 that it would stop producing paper charts.

Citing declining usage of paper charts due to digital and electronic charting systems and budget constraints, it said that limited print on demand (POD) versions would still be available. It was the end of a tradition begun by Thomas Jefferson, who established the first US Office of Coastal Survey in 1807. But these are the same people whose Navy stopped using “port” and “starboard” in preference to “left” and “right” because it caused “less confusion.”

It doesn’t look like New Zealand will be following that path anytime soon though. In April this year Land Information Minister Mark Mitchell announced a new ‘HYPLAN’ programme to keep up with the demands of charting our coastal waters.

“We’ll be prioritising seabed areas to be surveyed over the next 5–10 years, using the latest technology to produce the most accurate information available, for both digital and paper charts.

“We’ll prioritise the areas where it’s most beneficial,” he added, “like the Kaikoura to Port Underwood region. The seabed there was uplifted several metres in some places by the November 2016 earthquake in Kaikoura.”

Other areas to receive attention will be Fiordland, the Bay of Plenty and East Cape (due to increasing cruise ship traffic), Bluff and Rakiura/Stewart Island. The approaches to Port Taranaki, Banks Peninsula and Coromandel are also due for new surveys.

Most chart editions sell for $22.50 and chart agents are compelled by law to ensure that they’re up to date according to the publication details printed across the bottom margin. Most commercial ships are required by maritime law to carry charts, though certain classes of ship are exempt providing they have backup computers and power supply systems.

Just 10km off the Wellington coast, Cook Strait has the largest underwater canyon system in the world plunging to a depth of three kilometres (the Grand Canyon is 1.9km deep) off Cape Palliser. Scientists say that landslides within the system would be capable of triggering tsunamis.